With Packer 1.10.1 we started warning when a build failed to complete
because of a potential incompatibility with the builder being used.
This led to cases in which the build failed for other reasons, and
Packer would still warn of potential incompatibilities, even if the
builder was in effect HCP compatible.
We attempted to fix this issue by introducing a new error type, and
checks when we read the artifacts linked to a build, however this loop
would fail when any one of the artifacts is not compatible with HCP
Packer, leading to false failures.
To avoid this problem, we log incompatibilities to the verbose logger,
and only signal the problem if all the artifacts could not be used to
upload data to HCP Packer, in which case it's almost certain that if the
build succeeded and no artifacts are registered to the build, that all
the components used are not compatible with HCP, and should be reported
as such to users.